Rosemary essential oil (REO) is very promising as a therapeutic agent for various pathologies, especially as an antimicrobial. In spite of the growing interest in using REO and its major compound, it is necessary to perform toxicological studies to ensure that the chemical compounds found in the plant under study exert no adverse effects that would impair its use for therapeutic purposes. The purpose of this study is to determine whether rosemary essential oil and its major compound affect mouse fertility and fetal development during the organogenic period, which may trigger bone malformations. This study used pregnant females who received treatment orally (gavage) once a day from the 6^th to the 15^th day of gestation. They were divided according to the treatment received, and the groups studied included: Group I (negative control - Tween 80), Group II (1,8-cineole 134.55 mg.kg^-1), Group III (REO 300 mg.kg^-1), Group IV (REO 600 mg.kg^-1) and Group V (REO 1200 mg.kg^-1). The fetuses underwent the diaphanization technique and staining and were then individually assessed for the presence of bone changes. In females, signs of toxicity, birth rate, post-implantation losses, water and feed intake, and relative weight were assessed. The rats showed no signs of systemic toxicity, nor histopathological changes or alterations in the weight of analyzed organs that could infer any toxic effects. The administration of rosemary essential oil and its major compound 1,8-cineole did not cause differences in the reproductive rates studied in females. However, the treatments did interfere with fetal development, which was demonstrated through skeletal development delay in all groups studied. 1,8-cineole was the major compound of rosemary essential oil, as identified by chromatography. Groups IV, V and II showed a higher proportion of fetuses with skeletal abnormalities (78.31%, 100% and 95.06%, respectively). The alterations found in the fetuses of all studied groups suggest that exposure to these doses of the essential oil and 1,8-cineole should be avoided in pregnant women.